'So big and so happy': Voting underway in Alaska's annual Fat Bear Week contest

A contest to determine the beefiest brown bear is underway in Alaska. 

Fat Bear Week, a bracket-style, online-voting competition that began on Sept. 29, ends with a final matchup of salmon-slamming carnivores on Tuesday. 

The annual contest celebrates the success of brown bears that are preparing for hibernation around Brooks River in Katmai National Park and Bristol Bay, Alaska, by chunking up on salmon. 

Katmai Conservancy says the region is home to more brown bears than people, and the biggest sockeye salmon runs left on the planet.

"Because of these mass numbers of salmon, bears are allowed to get so fat," said Sara Wolman, project manager with Katmai Conservancy. 

The bears are in a state of hyperphagia, a drive to keep eating in order to store fat before winter.

A male bear named 747 was estimated to weigh more than 630 kilograms when he was crowned last year's winner, said Wolman. Some of the competition's 12 unwitting contestants have names, while others are numbered.